The present invention relates to a method for obtaining aromatics and/or dyestuffs from bell peppers by extraction of the pepper with a solvent.
The fruits of many of the about 50 cultured varieties of bell peppers (capsicum annuum or capsicum longum) contain aromatics and red dyestuffs. The aromatics contain fragrances and flavors and also contain the alkaloid, capsaicin which, even when greatly diluted, still has a very pungent taste. Bell pepper varieties have been grown which are free of capsaicin and are called "noble" sweet peppers. The aromatics of bell peppers can be used for the production of seasoning mixtures. The red dyestuffs of bell peppers contain carotinoids and their major component (up to 35%) is the carotinoid, capsanthin. The red dyestuffs are suitable for coloring foods and cosmetics and, because of their physiological harmlessness, are also approved as food dyes. In the food and cosmetics industry, the dyestuffs from bell peppers are used in the form of a liquid concentrate which is substantially free of impurities. For many applications, the dyestuff concentrate must not contain the aromatics of the pepper plant, particularly the capsaicin.
According to a known process, the aromatics and dyestuffs of bell peppers are obtained by extraction with a low boiling point solvent, such as, for example, dichloromethane, dichloroethane or hexane. From the extract obtained from the extraction, the aromatics and dyestuffs must be separated by way of a complicated molecular distillation since only the red dyestuffs which are free from aromatics are suitable for coloring many foodstuffs and cosmetics. Since bell peppers contain only small amounts of aromatics and dyestuffs (the dyestuff content of dried pepper is 1.4 to 5 percent by weight), large quantities of solvent are required for the pepper extraction, and these quantities of solvent must be recovered from the extract and the extraction residue by distillation or steam distillation in vacuo, respectively. In both cases, the organic solvent cannot be removed completely, particularly from the porous extraction residue, so that the losses of solvent are considerable and the use of the extraction residue as animal feed is greatly limited. Moreover, during the distillative removal of the solvent remainders from the extract, the higher temperatures required and/or the presence of oxygen may cause partial denaturization of the aromatics and dyestuffs in the extract.
German Auslegeschrift No. 1,493,190 discloses a process for separating mixtures of liquid and/or solid organic substances, wherein the mixture is treated with a gas whose temperature and pressure are in the supercritical state to form a charged supercritical gas phase. The treatment takes place in a temperature range up to 100.degree. C. above the critical temperature of the gas. After separation of the charged supercritical gas phase, the compounds contained therein are recovered by expansion and/or an increase in temperature. In this prior art process, saturated or unsaturated lower hydrocarbons, chlorinated or fluorinated hydrocarbons, carbon dioxide, ammonia or nitrous oxide can be used as the gaseous solvent.